Color images are customarily obtained in the photographic art by reaction between an oxidation product of a silver halide developing agent and a dye-forming coupler. Pyrazolone couplers are useful for forming magenta dye images; however, such couplers have shortcomings with respect to color reproduction in that the unwanted absorption around 430 nm causes color turbidity. Bicyclic pyrazolo couplers, particularly pyrazolotriazole couplers, represent another class of couplers for this purpose. Examples of pyrazoloazole couplers are described in, for example, U.S. Pat. No. 4,443,536; U.S. Pat. Nos. 1,247,493; 1,252,418; and 1,398,979; and U.S. Pat. Nos. 4,665,015; 4,514,490; 4,621,046, 4,540,654; 4,590,153; 4,822,730 and European Patents 177,765 and 119,860. One class of pyrazolotriazole couplers includes 1H-pyrazolo[3,2-c][1,2,4] triazole couplers and another includes 1H-pyrazolo[1,5-b][1,2,4] triazole couplers, such as described in European Patent 177765. While these couplers have a reduced level of unwanted absorption, the conversion of the coupler into an azomethine dye is slow and the maximum attainable density is reduced due to lower coupling efficiency.
Pyrazoloazole couplers containing a t-butyl group at the 6-position are described in U.S. Pat. No. 4,882,266. An example of such a coupler is: ##STR1## Such couplers suffer from the disadvantage of lower coupling reactivity manifested by lower contrast and Dmax as well as low speeds compared to the corresponding 6-methyl substituted analogs.
The existing products present a problem because they do not provide both acceptable reactivity, density and speed together with satisfactory photographic properties such as dye light stability color reproduction.